imaginAIry/imaginairy/modules/sgm/attention.py
Bryce 316114e660 docs: add docstrings
Wrote an openai script and custom prompt to generate them.
2023-12-15 14:32:01 -08:00

810 lines
26 KiB
Python

"""Classes for attention-based neural networks"""
import logging
import math
from inspect import isfunction
from typing import Any, Optional
import torch
import torch.nn.functional as F
from einops import rearrange, repeat
from packaging import version
from torch import nn
from torch.utils.checkpoint import checkpoint
logger = logging.getLogger(__name__)
if version.parse(torch.__version__) >= version.parse("2.0.0"):
SDP_IS_AVAILABLE = True
from torch.backends.cuda import SDPBackend, sdp_kernel
BACKEND_MAP = {
SDPBackend.MATH: {
"enable_math": True,
"enable_flash": False,
"enable_mem_efficient": False,
},
SDPBackend.FLASH_ATTENTION: {
"enable_math": False,
"enable_flash": True,
"enable_mem_efficient": False,
},
SDPBackend.EFFICIENT_ATTENTION: {
"enable_math": False,
"enable_flash": False,
"enable_mem_efficient": True,
},
None: {"enable_math": True, "enable_flash": True, "enable_mem_efficient": True},
}
else:
from contextlib import nullcontext
SDP_IS_AVAILABLE = False
sdp_kernel = nullcontext
BACKEND_MAP = {}
logger.warning(
f"No SDP backend available, likely because you are running in pytorch "
f"versions < 2.0. In fact, you are using PyTorch {torch.__version__}. "
f"You might want to consider upgrading."
)
try:
import xformers
import xformers.ops
XFORMERS_IS_AVAILABLE = True
except ImportError:
XFORMERS_IS_AVAILABLE = False
logger.debug("no module 'xformers'. Processing without...")
# from .diffusionmodules.util import mixed_checkpoint as checkpoint
def exists(val):
return val is not None
def uniq(arr):
return {el: True for el in arr}.keys()
def default(val, d):
if exists(val):
return val
return d() if isfunction(d) else d
def max_neg_value(t):
return -torch.finfo(t.dtype).max
def init_(tensor):
dim = tensor.shape[-1]
std = 1 / math.sqrt(dim)
tensor.uniform_(-std, std)
return tensor
# feedforward
class GEGLU(nn.Module):
def __init__(self, dim_in, dim_out):
super().__init__()
self.proj = nn.Linear(dim_in, dim_out * 2)
def forward(self, x):
x, gate = self.proj(x).chunk(2, dim=-1)
return x * F.gelu(gate)
class FeedForward(nn.Module):
def __init__(self, dim, dim_out=None, mult=4, glu=False, dropout=0.0):
super().__init__()
inner_dim = int(dim * mult)
dim_out = default(dim_out, dim)
project_in = (
nn.Sequential(nn.Linear(dim, inner_dim), nn.GELU())
if not glu
else GEGLU(dim, inner_dim)
)
self.net = nn.Sequential(
project_in, nn.Dropout(dropout), nn.Linear(inner_dim, dim_out)
)
def forward(self, x):
return self.net(x)
def zero_module(module):
"""
Zero out the parameters of a module and return it.
"""
for p in module.parameters():
p.detach().zero_()
return module
def Normalize(in_channels):
return torch.nn.GroupNorm(
num_groups=32, num_channels=in_channels, eps=1e-6, affine=True
)
class LinearAttention(nn.Module):
def __init__(self, dim, heads=4, dim_head=32):
super().__init__()
self.heads = heads
hidden_dim = dim_head * heads
self.to_qkv = nn.Conv2d(dim, hidden_dim * 3, 1, bias=False)
self.to_out = nn.Conv2d(hidden_dim, dim, 1)
def forward(self, x):
b, c, h, w = x.shape
qkv = self.to_qkv(x)
q, k, v = rearrange(
qkv, "b (qkv heads c) h w -> qkv b heads c (h w)", heads=self.heads, qkv=3
)
k = k.softmax(dim=-1)
context = torch.einsum("bhdn,bhen->bhde", k, v)
out = torch.einsum("bhde,bhdn->bhen", context, q)
out = rearrange(
out, "b heads c (h w) -> b (heads c) h w", heads=self.heads, h=h, w=w
)
return self.to_out(out)
class SelfAttention(nn.Module):
ATTENTION_MODES = ("xformers", "torch", "math")
def __init__(
self,
dim: int,
num_heads: int = 8,
qkv_bias: bool = False,
qk_scale: Optional[float] = None,
attn_drop: float = 0.0,
proj_drop: float = 0.0,
attn_mode: str = "xformers",
):
super().__init__()
self.num_heads = num_heads
head_dim = dim // num_heads
self.scale = qk_scale or head_dim**-0.5
self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
self.attn_drop = nn.Dropout(attn_drop)
self.proj = nn.Linear(dim, dim)
self.proj_drop = nn.Dropout(proj_drop)
assert attn_mode in self.ATTENTION_MODES
self.attn_mode = attn_mode
def forward(self, x: torch.Tensor) -> torch.Tensor:
B, L, C = x.shape
qkv = self.qkv(x)
if self.attn_mode == "torch":
qkv = rearrange(
qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads
).float()
q, k, v = qkv[0], qkv[1], qkv[2] # B H L D
x = torch.nn.functional.scaled_dot_product_attention(q, k, v)
x = rearrange(x, "B H L D -> B L (H D)")
elif self.attn_mode == "xformers":
qkv = rearrange(qkv, "B L (K H D) -> K B L H D", K=3, H=self.num_heads)
q, k, v = qkv[0], qkv[1], qkv[2] # B L H D
x = xformers.ops.memory_efficient_attention(q, k, v)
x = rearrange(x, "B L H D -> B L (H D)", H=self.num_heads)
elif self.attn_mode == "math":
qkv = rearrange(qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads)
q, k, v = qkv[0], qkv[1], qkv[2] # B H L D
attn = (q @ k.transpose(-2, -1)) * self.scale
attn = attn.softmax(dim=-1)
attn = self.attn_drop(attn)
x = (attn @ v).transpose(1, 2).reshape(B, L, C)
else:
raise NotImplementedError
x = self.proj(x)
x = self.proj_drop(x)
return x
class CrossAttention(nn.Module):
def __init__(
self,
query_dim,
context_dim=None,
heads=8,
dim_head=64,
dropout=0.0,
backend=None,
):
super().__init__()
inner_dim = dim_head * heads
context_dim = default(context_dim, query_dim)
self.scale = dim_head**-0.5
self.heads = heads
self.to_q = nn.Linear(query_dim, inner_dim, bias=False)
self.to_k = nn.Linear(context_dim, inner_dim, bias=False)
self.to_v = nn.Linear(context_dim, inner_dim, bias=False)
self.to_out = nn.Sequential(
nn.Linear(inner_dim, query_dim), nn.Dropout(dropout)
)
self.backend = backend
def forward(
self,
x,
context=None,
mask=None,
additional_tokens=None,
n_times_crossframe_attn_in_self=0,
):
h = self.heads
if additional_tokens is not None:
# get the number of masked tokens at the beginning of the output sequence
n_tokens_to_mask = additional_tokens.shape[1]
# add additional token
x = torch.cat([additional_tokens, x], dim=1)
q = self.to_q(x)
context = default(context, x)
k = self.to_k(context)
v = self.to_v(context)
if n_times_crossframe_attn_in_self:
# reprogramming cross-frame attention as in https://arxiv.org/abs/2303.13439
assert x.shape[0] % n_times_crossframe_attn_in_self == 0
n_cp = x.shape[0] // n_times_crossframe_attn_in_self
k = repeat(
k[::n_times_crossframe_attn_in_self], "b ... -> (b n) ...", n=n_cp
)
v = repeat(
v[::n_times_crossframe_attn_in_self], "b ... -> (b n) ...", n=n_cp
)
q, k, v = (rearrange(t, "b n (h d) -> b h n d", h=h) for t in (q, k, v))
with sdp_kernel(**BACKEND_MAP[self.backend]):
# print("dispatching into backend", self.backend, "q/k/v shape: ", q.shape, k.shape, v.shape)
out = F.scaled_dot_product_attention(
q, k, v, attn_mask=mask
) # scale is dim_head ** -0.5 per default
del q, k, v
out = rearrange(out, "b h n d -> b n (h d)", h=h)
if additional_tokens is not None:
# remove additional token
out = out[:, n_tokens_to_mask:]
return self.to_out(out)
class SlicedCrossAttention(nn.Module):
def __init__(
self,
query_dim,
context_dim=None,
heads=8,
dim_head=64,
dropout=0.0,
backend=None,
):
super().__init__()
inner_dim = dim_head * heads
context_dim = default(context_dim, query_dim)
self.scale = dim_head**-0.5
self.heads = heads
self.to_q = nn.Linear(query_dim, inner_dim, bias=False)
self.to_k = nn.Linear(context_dim, inner_dim, bias=False)
self.to_v = nn.Linear(context_dim, inner_dim, bias=False)
self.to_out = nn.Sequential(
nn.Linear(inner_dim, query_dim), nn.Dropout(dropout)
)
self.backend = backend
def forward(
self,
x,
context=None,
mask=None,
additional_tokens=None,
n_times_crossframe_attn_in_self=0,
slice_size=4096,
):
h = self.heads
if additional_tokens is not None:
# get the number of masked tokens at the beginning of the output sequence
n_tokens_to_mask = additional_tokens.shape[1]
# add additional token
x = torch.cat([additional_tokens, x], dim=1)
q = self.to_q(x)
context = default(context, x)
k = self.to_k(context)
v = self.to_v(context)
if n_times_crossframe_attn_in_self:
# reprogramming cross-frame attention as in https://arxiv.org/abs/2303.13439
assert x.shape[0] % n_times_crossframe_attn_in_self == 0
n_cp = x.shape[0] // n_times_crossframe_attn_in_self
k = repeat(
k[::n_times_crossframe_attn_in_self], "b ... -> (b n) ...", n=n_cp
)
v = repeat(
v[::n_times_crossframe_attn_in_self], "b ... -> (b n) ...", n=n_cp
)
q, k, v = (rearrange(t, "b n (h d) -> b h n d", h=h) for t in (q, k, v))
print(
"dispatching into backend",
self.backend,
"q/k/v shape: ",
q.shape,
k.shape,
v.shape,
)
if slice_size is not None:
out = self._sliced_attention(q, k, v, mask, slice_size)
else:
with sdp_kernel(**BACKEND_MAP[self.backend]):
# scale is dim_head ** -0.5 per default
out = F.scaled_dot_product_attention(q, k, v, attn_mask=mask)
del q, k, v
out = rearrange(out, "b h n d -> b n (h d)", h=h)
if additional_tokens is not None:
# remove additional token
out = out[:, n_tokens_to_mask:]
return self.to_out(out)
def _sliced_attention(self, q, k, v, mask, slice_size):
_, num_queries, _ = q.shape
output = torch.zeros_like(q)
for start_idx in range(0, num_queries, slice_size):
end_idx = min(start_idx + slice_size, num_queries)
q_slice = q[:, start_idx:end_idx, :]
mask_slice = None
if mask is not None:
mask_slice = mask[:, start_idx:end_idx, :]
with sdp_kernel(**BACKEND_MAP[self.backend]):
out_slice = F.scaled_dot_product_attention(
q_slice, k, v, attn_mask=mask_slice
)
output[:, start_idx:end_idx, :] = out_slice
return output
class MemoryEfficientCrossAttention(nn.Module):
# https://github.com/MatthieuTPHR/diffusers/blob/d80b531ff8060ec1ea982b65a1b8df70f73aa67c/src/diffusers/models/attention.py#L223
def __init__(
self, query_dim, context_dim=None, heads=8, dim_head=64, dropout=0.0, **kwargs
):
super().__init__()
logger.debug(
f"Setting up {self.__class__.__name__}. Query dim is {query_dim}, "
f"context_dim is {context_dim} and using {heads} heads with a "
f"dimension of {dim_head}."
)
inner_dim = dim_head * heads
context_dim = default(context_dim, query_dim)
self.heads = heads
self.dim_head = dim_head
self.to_q = nn.Linear(query_dim, inner_dim, bias=False)
self.to_k = nn.Linear(context_dim, inner_dim, bias=False)
self.to_v = nn.Linear(context_dim, inner_dim, bias=False)
self.to_out = nn.Sequential(
nn.Linear(inner_dim, query_dim), nn.Dropout(dropout)
)
self.attention_op: Optional[Any] = None
def forward(
self,
x,
context=None,
mask=None,
additional_tokens=None,
n_times_crossframe_attn_in_self=0,
):
if additional_tokens is not None:
# get the number of masked tokens at the beginning of the output sequence
n_tokens_to_mask = additional_tokens.shape[1]
# add additional token
x = torch.cat([additional_tokens, x], dim=1)
q = self.to_q(x)
context = default(context, x)
k = self.to_k(context)
v = self.to_v(context)
if n_times_crossframe_attn_in_self:
# reprogramming cross-frame attention as in https://arxiv.org/abs/2303.13439
assert x.shape[0] % n_times_crossframe_attn_in_self == 0
# n_cp = x.shape[0]//n_times_crossframe_attn_in_self
k = repeat(
k[::n_times_crossframe_attn_in_self],
"b ... -> (b n) ...",
n=n_times_crossframe_attn_in_self,
)
v = repeat(
v[::n_times_crossframe_attn_in_self],
"b ... -> (b n) ...",
n=n_times_crossframe_attn_in_self,
)
b, _, _ = q.shape
q, k, v = (
t.unsqueeze(3)
.reshape(b, t.shape[1], self.heads, self.dim_head)
.permute(0, 2, 1, 3)
.reshape(b * self.heads, t.shape[1], self.dim_head)
.contiguous()
for t in (q, k, v)
)
# print(
# "q/k/v shape: ",
# q.shape,
# k.shape,
# v.shape,
# )
# actually compute the attention, what we cannot get enough of
if version.parse(xformers.__version__) >= version.parse("0.0.21"):
# NOTE: workaround for
# https://github.com/facebookresearch/xformers/issues/845
max_bs = 32768
N = q.shape[0]
n_batches = math.ceil(N / max_bs)
out = []
for i_batch in range(n_batches):
batch = slice(i_batch * max_bs, (i_batch + 1) * max_bs)
out.append(
xformers.ops.memory_efficient_attention(
q[batch],
k[batch],
v[batch],
attn_bias=None,
op=self.attention_op,
)
)
out = torch.cat(out, 0)
else:
out = xformers.ops.memory_efficient_attention(
q, k, v, attn_bias=None, op=self.attention_op
)
# TODO: Use this directly in the attention operation, as a bias
if exists(mask):
raise NotImplementedError
out = (
out.unsqueeze(0)
.reshape(b, self.heads, out.shape[1], self.dim_head)
.permute(0, 2, 1, 3)
.reshape(b, out.shape[1], self.heads * self.dim_head)
)
if additional_tokens is not None:
# remove additional token
out = out[:, n_tokens_to_mask:]
return self.to_out(out)
class BasicTransformerBlock(nn.Module):
ATTENTION_MODES = {
"softmax": CrossAttention, # vanilla attention
"softmax-xformers": MemoryEfficientCrossAttention, # ampere
}
def __init__(
self,
dim,
n_heads,
d_head,
dropout=0.0,
context_dim=None,
gated_ff=True,
checkpoint=True,
disable_self_attn=False,
attn_mode="softmax",
sdp_backend=None,
):
super().__init__()
assert attn_mode in self.ATTENTION_MODES
if attn_mode != "softmax" and not XFORMERS_IS_AVAILABLE:
logger.debug(
f"Attention mode '{attn_mode}' is not available. Falling "
f"back to native attention. This is not a problem in "
f"Pytorch >= 2.0. FYI, you are running with PyTorch "
f"version {torch.__version__}."
)
attn_mode = "softmax"
elif attn_mode == "softmax" and not SDP_IS_AVAILABLE:
logger.warning(
"We do not support vanilla attention anymore, as it is too "
"expensive. Sorry."
)
if not XFORMERS_IS_AVAILABLE:
msg = "Please install xformers via e.g. 'pip install xformers==0.0.16'"
raise RuntimeError(msg)
else:
logger.info("Falling back to xformers efficient attention.")
attn_mode = "softmax-xformers"
attn_cls = self.ATTENTION_MODES[attn_mode]
if version.parse(torch.__version__) >= version.parse("2.0.0"):
assert sdp_backend is None or isinstance(sdp_backend, SDPBackend)
else:
assert sdp_backend is None
self.disable_self_attn = disable_self_attn
self.attn1 = attn_cls(
query_dim=dim,
heads=n_heads,
dim_head=d_head,
dropout=dropout,
context_dim=context_dim if self.disable_self_attn else None,
backend=sdp_backend,
) # is a self-attention if not self.disable_self_attn
self.ff = FeedForward(dim, dropout=dropout, glu=gated_ff)
self.attn2 = attn_cls(
query_dim=dim,
context_dim=context_dim,
heads=n_heads,
dim_head=d_head,
dropout=dropout,
backend=sdp_backend,
) # is self-attn if context is none
self.norm1 = nn.LayerNorm(dim)
self.norm2 = nn.LayerNorm(dim)
self.norm3 = nn.LayerNorm(dim)
self.checkpoint = checkpoint
if self.checkpoint:
logger.debug(f"{self.__class__.__name__} is using checkpointing")
def forward(
self, x, context=None, additional_tokens=None, n_times_crossframe_attn_in_self=0
):
kwargs = {"x": x}
if context is not None:
kwargs.update({"context": context})
if additional_tokens is not None:
kwargs.update({"additional_tokens": additional_tokens})
if n_times_crossframe_attn_in_self:
kwargs.update(
{"n_times_crossframe_attn_in_self": n_times_crossframe_attn_in_self}
)
# return mixed_checkpoint(self._forward, kwargs, self.parameters(), self.checkpoint)
if self.checkpoint:
# inputs = {"x": x, "context": context}
return checkpoint(self._forward, x, context)
# return checkpoint(self._forward, inputs, self.parameters(), self.checkpoint)
else:
return self._forward(**kwargs)
def _forward(
self, x, context=None, additional_tokens=None, n_times_crossframe_attn_in_self=0
):
x = (
self.attn1(
self.norm1(x),
context=context if self.disable_self_attn else None,
additional_tokens=additional_tokens,
n_times_crossframe_attn_in_self=n_times_crossframe_attn_in_self
if not self.disable_self_attn
else 0,
)
+ x
)
x = (
self.attn2(
self.norm2(x), context=context, additional_tokens=additional_tokens
)
+ x
)
x = self.ff(self.norm3(x)) + x
return x
class BasicTransformerSingleLayerBlock(nn.Module):
ATTENTION_MODES = {
"softmax": CrossAttention, # vanilla attention
"softmax-xformers": MemoryEfficientCrossAttention # on the A100s not quite as fast as the above version
# (todo might depend on head_dim, check, falls back to semi-optimized kernels for dim!=[16,32,64,128])
}
def __init__(
self,
dim,
n_heads,
d_head,
dropout=0.0,
context_dim=None,
gated_ff=True,
checkpoint=True,
attn_mode="softmax",
):
super().__init__()
assert attn_mode in self.ATTENTION_MODES
attn_cls = self.ATTENTION_MODES[attn_mode]
self.attn1 = attn_cls(
query_dim=dim,
heads=n_heads,
dim_head=d_head,
dropout=dropout,
context_dim=context_dim,
)
self.ff = FeedForward(dim, dropout=dropout, glu=gated_ff)
self.norm1 = nn.LayerNorm(dim)
self.norm2 = nn.LayerNorm(dim)
self.checkpoint = checkpoint
def forward(self, x, context=None):
# inputs = {"x": x, "context": context}
# return checkpoint(self._forward, inputs, self.parameters(), self.checkpoint)
return checkpoint(self._forward, x, context)
def _forward(self, x, context=None):
x = self.attn1(self.norm1(x), context=context) + x
x = self.ff(self.norm2(x)) + x
return x
class SpatialTransformer(nn.Module):
"""
Transformer block for image-like data.
First, project the input (aka embedding)
and reshape to b, t, d.
Then apply standard transformer action.
Finally, reshape to image
NEW: use_linear for more efficiency instead of the 1x1 convs
"""
def __init__(
self,
in_channels,
n_heads,
d_head,
depth=1,
dropout=0.0,
context_dim=None,
disable_self_attn=False,
use_linear=False,
attn_type="softmax",
use_checkpoint=True,
# sdp_backend=SDPBackend.FLASH_ATTENTION
sdp_backend=None,
):
super().__init__()
logger.debug(
f"constructing {self.__class__.__name__} of depth {depth} w/ "
f"{in_channels} channels and {n_heads} heads."
)
if exists(context_dim) and not isinstance(context_dim, list):
context_dim = [context_dim]
if exists(context_dim) and isinstance(context_dim, list):
if depth != len(context_dim):
logger.warning(
f"{self.__class__.__name__}: Found context dims "
f"{context_dim} of depth {len(context_dim)}, which does not "
f"match the specified 'depth' of {depth}. Setting context_dim "
f"to {depth * [context_dim[0]]} now."
)
# depth does not match context dims.
assert all(
x == context_dim[0] for x in context_dim
), "need homogenous context_dim to match depth automatically"
context_dim = depth * [context_dim[0]]
elif context_dim is None:
context_dim = [None] * depth
self.in_channels = in_channels
inner_dim = n_heads * d_head
self.norm = Normalize(in_channels)
if not use_linear:
self.proj_in = nn.Conv2d(
in_channels, inner_dim, kernel_size=1, stride=1, padding=0
)
else:
self.proj_in = nn.Linear(in_channels, inner_dim)
self.transformer_blocks = nn.ModuleList(
[
BasicTransformerBlock(
inner_dim,
n_heads,
d_head,
dropout=dropout,
context_dim=context_dim[d],
disable_self_attn=disable_self_attn,
attn_mode=attn_type,
checkpoint=use_checkpoint,
sdp_backend=sdp_backend,
)
for d in range(depth)
]
)
if not use_linear:
self.proj_out = zero_module(
nn.Conv2d(inner_dim, in_channels, kernel_size=1, stride=1, padding=0)
)
else:
# self.proj_out = zero_module(nn.Linear(in_channels, inner_dim))
self.proj_out = zero_module(nn.Linear(inner_dim, in_channels))
self.use_linear = use_linear
def forward(self, x, context=None):
# note: if no context is given, cross-attention defaults to self-attention
if not isinstance(context, list):
context = [context]
b, c, h, w = x.shape
x_in = x
x = self.norm(x)
if not self.use_linear:
x = self.proj_in(x)
x = rearrange(x, "b c h w -> b (h w) c").contiguous()
if self.use_linear:
x = self.proj_in(x)
for i, block in enumerate(self.transformer_blocks):
if i > 0 and len(context) == 1:
i = 0 # use same context for each block
x = block(x, context=context[i])
if self.use_linear:
x = self.proj_out(x)
x = rearrange(x, "b (h w) c -> b c h w", h=h, w=w).contiguous()
if not self.use_linear:
x = self.proj_out(x)
return x + x_in
class SimpleTransformer(nn.Module):
def __init__(
self,
dim: int,
depth: int,
heads: int,
dim_head: int,
context_dim: Optional[int] = None,
dropout: float = 0.0,
checkpoint: bool = True,
):
super().__init__()
self.layers = nn.ModuleList([])
for _ in range(depth):
self.layers.append(
BasicTransformerBlock(
dim,
heads,
dim_head,
dropout=dropout,
context_dim=context_dim,
attn_mode="softmax-xformers",
checkpoint=checkpoint,
)
)
def forward(
self,
x: torch.Tensor,
context: Optional[torch.Tensor] = None,
) -> torch.Tensor:
for layer in self.layers:
x = layer(x, context)
return x